Given an array list, and the count of element on the list find the location of the largest element using recursion.
So far, I'm able to find the largest element, but I need the location of that element on the array and not the actual value.
private int getLargestElementLoca(int[] list, int count)
{
int largestValue;
if(count == 1){
return 0;
}
int tempMax = getLargestElementLoca(list,count-1);
largestValue = Math.max(list[count-1],tempMax);
return largestValue;
}
You're on the right track, but you just need some tweaks. I'm not going to write the code for you, but here are some clues.
If you want your function to return the index instead of the maximum value, then you need to change the way you compute the return value and the way you use it recursively.
private int getLargestElementLoca(int[] list, int count)
{
int largestValue;
if(count == 1){
return 0;
}
If there is only one element to look at, i.e. list[0], then list[0] will be the maximum, and 0 will be its index. So returning 0 is correct here.
int tempMax = getLargestElementLoca(list,count-1);
You've redefined getLargestElementLoca so that it returns an index, not a maximum value. That applies to your recursive call also, so tempMax is going to be an index and not a value. That means that you can't pass it directly into Math.max. Some adjustment will be necessary, but keep reading.
largestValue = Math.max(list[count-1],tempMax);
Math.max returns the largest value, but that isn't what you want. You have two indexes, count-1 and something else, and you want to compute the index of the larger value. You can't do that with Math.max, but you can use an if statement or the conditional operator a ? b : c. It would also be helpful to rename the variable, since it's no longer going to contain the largest value.
list[n] where n is some other index. That's all I'll say, but you should be able to figure out by rereading my answer what that other index is.An idea could be to split your array recursiv into two parts until there are only 2 or 1 elements remainning. Finding the max value in two numbers or one is simple und return it. Then you compare the two returned values and return the max.
Recursion is simple, but you should know about doing it iteratively:
private int getMaxLocation(int[] array) {
int maxpos = 0;
int max = Integer.MIN_VALUE;
for (int i = 0; i < array.length; i++) {
if (array[i] > max) {
max = array[i];
maxpos = i;
}
}
return maxpos;
}
If you were to do this through recursion, you would need to track a few variables across it:
private int getMaxLocation(int[] array, int pos, int max, int maxpos) {
if (pos >= array.length || pos < 0) {
return maxpos;
} else {
int current = array[pos];
if (current > max) {
max = current;
maxpos = pos;
}
return getMaxLocation(array, ++pos, max, maxpos);
}
}
//calling this
int max = getMaxLocation(yourArray, 0, Integer.MIN_VALUE, 0);